This invention relates generally to video graphics and more particularly to supplying images to multiple displays from a drawing surface.
Computers are known to comprise a central processing unit, system memory, audio processing circuitry, peripheral ports, and video processing circuitry. The peripheral ports allow the central processing unit to communicate with peripheral devices such as monitors, printers, external tape drives, the Internet, etc. The video graphics circuitry functions as a co-processor to the central processing unit to perform video graphic functions. As such, the video graphics processor receives graphical data generated by the central processing unit and renders the graphical data into pixel data that is subsequently displayed on a monitor.
The video graphics circuitry may be coupled to a single display or multiple displays. When coupled to a single display, a frame buffer holds the pixel data that will subsequently be provided to the display. Typically, the pixel data is mapped into the frame buffer based on physical parameters of the monitor (e.g., resolution and X-Y coordinates). The mapping of the frame buffer may be linear mapping or tile mapping. Regardless of the mapping techniques, the display presents in a full screen the images stored in the frame buffer.
When the video graphics processing circuit is supplying pixel data to multiple displays, one or more of the displays may be operating in a virtual desktop mode. A display will operated in the virtual desktop mode when its resolution does not match the resolution of one or more of the other multiple displays. Typically, the display operating in the virtual desktop mode has a lower resolution than the other displays, thus it is too small to display the full image of the data stored in the frame buffer. When in the virtual desktop mode, only a portion of the image in the frame buffer is presented on screen. To view other portions of the image, a mouse, or other GUI action is performed.
While the virtual desktop mode allows multiple displays to display the same image from a frame buffer, virtual desktop operations are primarily equipment controlled. In particular, the equipment (i.e., hardware and/or software) selects the resolution for the multiple displays, including those that operate in the virtual desktop mode. Typically, the resolution of the largest display, i.e., the one having the largest resolution, is chosen. As such, the other displays operate in the virtual desktop mode.
As display technology continues to advance, a display may operation in several different modes. For example, the display""s resolution may be changed from 640xc3x97480 to 720xc3x97540, 1024xc3x97768, etc., the display""s refresh rate may be changed from 60 Hz to 75 Hz, 90 Hz, etc, and the display""s pixel depth may be changed from 8 pixels to 16 pixels, 24 pixels, 32 pixels, etc. When such a display is used in a virtual desktop mode, the added modes of operation are not utilized. In addition, a user is not able to select operating modes of multiple displays that are displaying the same images from a frame buffer.
Therefore, a need exists for a method and apparatus that provides greater flexibility to the user in selecting setup options for displaying images on multiple screens.